User beware! For unexplained reasons, all of the information required to interpret this chart is missing. The vertical scale is missing, which means that we do not know how many searches include the word "blog". While the relative gap between the lines is large, the absolute difference may in fact be tiny.

Also, what sample size was used? How were the samples selected? This gets even more tricky because Google then categorizes the results by cities, regions and languages. Do they have enough samples to make meaningful statements at that level of detail? Similarly, on the time scale, what kind of smoothing was employed?

This isn't just another google-bashing rant. It is a thoughtful and useful analysis. I'll keep on using Google Trends, because it's a unique tool. But this piece makes a very clear case as to why the results should be taken with a grain of salt.